1. Field of the Invention
This invention relates to magnetic reed switches and, more particularly, to brackets for mounting a reed switch and an associated magnet on the guide track of an overhead security door.
2. Description of Related Art
A reed switch is a mechanical electrical switch having a pair of ferromagnetic contacts in either a normally-open or normally-closed configuration. In the presence of a magnetic field, the contacts of a normally-open reed switch will close, while the contacts of a normally-closed reed switch will open. Reed switches are typically used as proximity sensors for limit, safety, and security applications.
The present invention is designed for security applications. Overhead security doors are generally mounted between two parallel tracks. For buildings having a height at least double the door height, the tracks may be entirely vertical. However, for buildings having a height less than double the door height, vertical tracks are used for the closed door position, and horizontal tracks are used for the open position. The vertical and horizontal tracks are interconnected by curved sections. As a general rule, overhead doors are secured by a pair of bolts which can be horizontally extended or retracted by rotating a locking handle coupled to both bolts. When the door is fully closed and the bolts are in their extended positions, one bolt is inserted within an aperture in one of the tracks, and the other bolt is inserted within an aperture in the opposite track.
What is needed is a bracket assembly for securely mounting a reed switch and its associated magnet on at least one of the tracks of an overhead door, such that the reed switch and magnet are on opposite sides of the bolt-receiving aperture of the track. If ferromagnetic bolts are employed to lock the door, the bolt will interfere with the magnetic field generated by the magnet so that the reed switch will be unaffected by the magnetic field as long as the bolt is in its locked position. When the bolt is withdrawn from the bolt-receiving aperture, the magnetic field acts on the reed switch to generate a signal. The bracket assembly should, ideally, provide an enclosure which will protect both the reed switch and the magnet from inadvertent mechanical damage. In addition, the bracket assembly should be relatively inexpensive manufacture and simple to install, and readily disassemblable for reed switch replacement.